China lost control over a rocket delivering a section of the Tiangong space station

So China launched a Long March 5 rocket on Apr 29 to deliver the core section of their new Tiangong space station. They have lost control of the rocket in low orbit and the rocket is on it’s way back into the atmosphere. The US army has named this object 2021-035B.

There is no telling where or when 2021-035B will make impact. It will pass over Taiwan around tonight at midnight.

A similar event happened last year, when China lost control over another Long March 5 rocket, when ended up crashing into the Atlantic near West Africa last May. A 12 meter long section crashing into a village in Ivory Coast.


Havent read about it, but not super surprised if true.

For those interested to see where it currently is.

It’s true. The chance of getting hit by falling debris is minute, but still…

"Jonathan McDowell, a Harvard astrophysicist and orbital object tracker, noted at the time that the Long March 5B core was the heaviest object to make an uncontrolled reentry through the atmosphere in nearly three decades. "

What was the last heavy one to fall? Mir?

Im glad we still support chinese manufactring and diligence. At least space stuff isnt made by literal slaves… one would hope.

1991, when the 43-ton (39,000 kg) Salyut-7 Soviet space station fell through the atmosphere over Argentina

In May 2020, a Long March 5B rocket slammed through the atmosphere, partially burning up on its descent, Live Science previously reported. The core fell largely into the Atlantic Ocean, but some debris landed in West Africa. According to the [South China Morning Post]

from this article:


I don’t quite understand this tracker but it is interesting. CZ-5B / 48275 / 2021-035B - Satellite Orbit Data

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It appears to be in an elliptical orbit a long way above the atmosphere, so presumably it’ll take a good while for the orbit to decay and rain molten trash onto Taipei, um, I mean into the ocean.

TBH I don’t understand why its orbit is decaying as fast as it is. Any orbital-mechanics experts here?




I think it is currently losing altitude at the pace of 520m per hour (12.5km per day). But it is gaining velocity.

Because it’s losing altitude (=falling). Its gravitational potential energy is being converted to kinetic energy.

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If the rate of altitude decline is linear (which it shouldn’t be because gravity), it will take another 25 days to come down.

I guess it’s hard to predict at this point. The rate at which it bleeds off kinetic energy will start to increase as the atmosphere gets thicker. So probably somewhat less than that. I’m just waiting to see if it’s not as “out of control” as they make out. If de-orbiting occurs at a suspiciously precise moment and angle of entry, I’ll be hiding in the basement.

Very surprised it’s that rapid though. I was under the impression you could maintain something in that sort of orbit for years.

EDIT: ah, no, apparently not. The ISS uses a shitload of propellant to keep itself up there at 400km.


Such a china thing to do. They want the recognition of being a super power and developed nation without any of the responsibilities.


I wonder what the terminal velocity would be for a 21 ton 30x5 steel cylinder.

Vt = √(2mg/ρACd)

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CCP in space is basically Space Balls 2.


Perhaps more importantly … how much kinetic energy is it going to have left when it drops on top of my apartment building.

Complete with their very own bellend running the show.



Gonna need some serious Schwartz to stop that thing. Regrettably, very unsurprising it’s China again…

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Just did the math, assuming it’s always the long side of the cylinder falling towards Earth, the terminal velocity is going to be 30.252 m/s, which would be 108.9072 km/h, actually not that fast…

If it’s flipping around, then it’s going to fall faster.

Oh, and I assumed it’s just steel, if it’s built with something denser, then it’s also going to fall faster.

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